Process of preparing luminous surfaces



June 25, 1929.

w. F. B LEECKER PROCESS OF PREPARING LUMINOUS SURFACES Filed Oct. 9, 1922 Fig.2

55 WP a wm ATTORNEY.

to a surface,- which produces ahigh degree of Patented June 25, 1929.

UNITED STATES 1,718,626 PATENT OFFKIE.

' WARREN r. IBLEECKER, or BOULDER, COLORADO.

I PRQCESS OF PREPARING LUMINOUS SURFACES.

Application filed October 9,1922. Serial lie. 593,479.

My invention relates to a process of preparing luminous surfaces and its prmclpal object is to provide a method ofapplymg radio-active and radio-receptive substances tion of light. If, for example, the radioresponsive substance with the thereto adhering radio-active particles is intermixed with a varnish or other similar adhesive, to form a liquidor semi-liquid paint, the crystals of the radio responsive substance are covered over their entire extent, and when the surface to be rendered luminous, is coated with the mixture, only the radium on the exposed surfaces of the outer stratum of the granules is capable of emanating its rays, while that on the underside of the outer particles or that on the crystals which are covered by the outer layer, is prevented from adding to the. luminosity of the surface and is consequently wasted. In another prior method of coating surfaces to render them luminous, the surface is, for example, first covered with the radio-responsive material which in turn is covered en masse with the radio-active material inpulverulent form. It is practically impossible in this method to so apply the radium dust that each particle is separatel exposed at the surface and a waste of va uable material is again unavoidable. Moreover, in each of the two processes, a smooth coating is produced so that the luminosity of the exposed self-luminous material is limited by the superficial area of the surface to which it is applied.

In the process of preparing a luminous surface according to the present invention, all waste of the kind above referred to is avoided and the luminous extent of the surface per unit area, is moreover increased, by first applying the crystalline radio-responsive material in a dry state to the surface, and then coating the exposed faces of its particles with a radium compound in solution. It will be evident that the crystals of the radio-receptive substance thus applied, present an irregular surface the area of which exceeds thesuperficial extent of the surface to which it adheres, and that by applying the radium in solution, it is aflixed to the exposed faces of the crystals in a thin film of uniform thickness which precludes the waste encountered in other methods as stated hereinbeore.

In carrying out my invention, for'example, I paint the surface or design to be made luminous, with a thin coating of varnish or other glutinous material, cover the wet surface with a coating of granular zinc sulfide or other radio-responsive substance in crystalline form, by dusting, blowing, pressing or othersimilar method, remove the surplus sulfide after the varnish has dried, and finally coat the exposed surfaces of the crystals adhering to the varnish, with a neutral.

or nearly neutral solution of radium salt such as radium chloride, radium bromide, etc., that does not dissolve the responsive crystals or substance.

It will be apparent from the above description that my process has another valuable advantage over other methods in that it permits of the application of the radio- 'active and radio-responsive substances, one

upon the other, in any desired design, since the glutinous substance can be applied to the surface by means of a brush, printing" press, stamping press or any other known method of making or impressing pictorial, typographical or other representations upon a surace.

In the accompanying drawing, I have shown in Figure 1 a letter rendered luminous by my process;

Figure 2, represents a portion of the faceof the letter drawn to an exaggerated scale;

Figure 3, a still further magnified section'- taken on the line 33, Figure 2; and

Figure 4, a still further magnified section showing the distribution of the radio-active material upon the crystals of the radio-responsive material. v

The reference character 2 designates the object to which the materials are applied, 3 is the glutinous coating, 4 the zinc sulfide crystals adhering to the coating, and 5 the film of radium compound applied in solution, to the crystals. u

It will be observed that the total extent of the radio-active film covering the angularly 2 p unease disposed faces of the exposed portions of the crystals, is far in excess of the superficial area of the design to which the coating is applied and that the luminosity of the design 1s correspondingly increased. It will furthermore be apparent that inasmuch as thesulfidc crystals adhere to the glutinous coating, contiguous to each other, onl their exposed faces can receive the film o radio-active solution and that each article of the radium compound thus app ied is continuously active in emanating its alpha rays.

I desire it understood that within the spirit of my invention anyradio-responsive material in crystalline form, such as the sulfides of zinc, barium, calcium or strontium, artificial willemite, or others, and any radio-active excitant, such as salts of radium, actinium, ionium, mesothonium, uranium or others, may be employed with varying results and that any glue, varnish or other rapidly drying liquid.

adhesive is suitable to coat the surface to be rendered luminous.

In the drawings, the crystals of the radioresponsive material have been represented as those ofzinc sulfide.

I regulate the predetermined degree of luminosit of the coated surface by varying or establis ing the strength of the radium solution. I have found that for all ordinary purposes, a solution of forty micrograms of radium element in one cubic centimeter of water or other suitable solvent, is sufiicient to give luminosity equal to that now provided in commercial use, as in watch figures and hands, or to render other articles luminous.

After a design has been rendered self-luminous bymy process,its surfacemay be made more durable by treating it with a soluble sulfate to render insoluble the radium in place, as radium sulfate, which is insoluble in water. The radium-covered surface of the design may also be protected by a thin coating of transparent varnish or it may be covered with glass or other similar transparent material.

I desire it understood that the drawings are merely intended to illustrate the process and that I do not limit myself to the particular embodiments of my invention therein shown and hereinbefore described.

What I claim and desire tosecure by Letters Patent is:

1. The method of preparing a luminous surface, consisting in first coating the surface with an adhesive, applying a radio-responslve substance 'to the adhesive, and coverin said substance with a radio-active material m solution. h a

2. The method of preparing a; luminou surface, consisting in first coating the surface with an adhesive, applying a radio-responsive substance to the adhesive and cover mg said substance .with a radium compound in solution.

3. The method of preparing a luminous surface, consisting in first coating the surface with an adhesive,.applying a radio-responsive substance to the adhesive, covering said substance with a radio-active material in solution, and finally treating the material with a soluble sulfate.

4. The method of preparing a luminous surface consisting in covering a radio-responsive material on the surface, with a film of radio-active material in solution.

5. The method of preparing a luminous surface consisting in covering a radio-responsive material on the surface, with a film of radio-active material in solution, and then rendering the radio-active material insoluble.

6. The method of preparing a luminous surface consisting in covering a. radio-responsive material on the surface, with a film of radioactive material in solution, and then coating said film with a transparent substance.

7. The method of preparing a luminous surface consisting in covering a radio-responsive material on the surface, with a film of radio-activematerial in solution, then rendering the radio-active material insoluble and finally applying a protective transparent covering to the film.

8. The method of preparing a luminous surface, consisting in covering a. radio-responsive material on the surface, with a film of radio-active material in solution, and then coating said film with a soluble sulfate.

In testimony whereof I have aifixed my signature. V WARREN F. BLEECKER. 

